1. Field of the Invention
The present invention relates generally to surgical instruments and pertains, more specifically, to surgical instruments used in connection with the insertion and subsequent removal of implants.
2. Description of the Invention Background
The use of prosthetic devices to replace the natural joints of the body, either as a result of disease or injury to the natural joint, is commonplace. For example, in hip arthroplasty, it is necessary to replace the natural femoral head with a femoral implant having a stem portion which enters the medullary canal of the femur and another portion which provides an accurately located and securely held prosthetic head in place of the natural femoral head. To aid in the insertion of a femoral prothesis, tools are available that couple or grasp the prosthesis to enable the surgeon to manipulate the prosthesis for appropriate positioning during the procedure and to impact the prosthesis during implantation. The same tool or a different tool may be available for the subsequent extraction of the femoral prosthesis, if necessary. Prior to the insertion of the femoral implant, a broach is used to size the femoral canal. Typically, the broach is connected to its own tool to be grasped by the surgeon for manipulation during sizing of the femoral canal.
The most commonly used method of attaching a tool to an implant or broach is by complementary threads in the implant and the tool. A threaded hole is tapped in the implant itself. A matching threaded male portion on the instrument is screwed into the threaded hole, and the implant can then be manipulated. When the tool is removed, a cavity remains in the implant. A screw is sometimes used to fill the hole after the prosthesis is implanted. Even when screws are used, however, debris can collect in the cavity which can interfere with and even prevent the insertion of the male thread of the tool into the threaded hole of the implant. In addition, the collection of debris in the threads of tools create problems in maintaining clean tools and can make cleaning and sterilization of tools more time consuming.
In implant tools using threaded components, manufacturing of the internal threads can be very difficult and expensive in some materials, such as cobalt-chrome and titanium. The torque required for tapping these materials usually exceeds the capability of the material of the taps themselves, resulting in broken or dulled taps. Furthermore, insertion of the femoral implant into the femoral canal often requires impacting the tool with a mallet to drive the implant into the final position. Impacting the insertion tools can cause the threads to become slack or loose. This loosening can cause the surgeon to lose his feel for, and therefore sacrifice precision in, the proper seating of the implant in the femoral canal. Additionally, threaded instruments must be rotated approximately 3-10 revolutions to attach the instrument to the implant and another 3-10 revolutions to detach the instrument from the implant.
There is a need for a tool for use in inserting and removing both prostheses and broaches to reduce the number of tools a surgeon requires during an implant procedure. There is a further need for such a tool which eliminates cavities in the implant in which debris can accumulate. Finally, there is a need for a tool which can be connected and disconnected quickly to reduce the time for engaging a tool to an implant or a broach and the risk of infection associated therewith.